8282769: BSD date cannot handle all ISO 8601 formats

Reviewed-by: erikj

Author: magicus

make/autoconf/util.m4

@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2011, 2021, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2011, 2022, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
@@ -230,8 +230,6 @@ AC_DEFUN([UTIL_GET_MATCHING_VALUES],
 # Converts an ISO-8601 date/time string to a unix epoch timestamp. If no
 # suitable conversion method was found, an empty string is returned.
 #
-# Sets the specified variable to the resulting list.
-#
 # $1: result variable name
 # $2: input date/time string
 AC_DEFUN([UTIL_GET_EPOCH_TIMESTAMP],
@@ -241,11 +239,11 @@ AC_DEFUN([UTIL_GET_EPOCH_TIMESTAMP],
     timestamp=$($DATE --utc --date=$2 +"%s" 2> /dev/null)
   else
     # BSD date
-    timestamp=$($DATE -u -j -f "%F %T" "$2" "+%s" 2> /dev/null)
+    timestamp=$($DATE -u -j -f "%FZ %TZ" "$2" "+%s" 2> /dev/null)
     if test "x$timestamp" = x; then
-      # Perhaps the time was missing
-      timestamp=$($DATE -u -j -f "%F %T" "$2 00:00:00" "+%s" 2> /dev/null)
-      # If this did not work, we give up and return the empty string
+      # BSD date cannot handle trailing milliseconds.
+      # Try again ignoring characters at end
+      timestamp=$($DATE -u -j -f "%Y-%m-%dT%H:%M:%S" "$2" "+%s" 2> /dev/null)
     fi
   fi
   $1=$timestamp